Some researchers believe not having enough vitamin D can raise the risk of heart disease in people with diabetes. And a study suggests a way in which it might happen. Carlos Bernal-Mizrachi of Washington University of St. Louis looked at cells called macrophages, which remove excess cholesterol. He thinks the macrophages of people with diabetes and low vitamin D get clogged with cholesterol – macrophages’ signaling pathways are impeded by low levels of vitamin D. But he says: "To replace it to normal levels would be an easy thing to do with not much complications." In summer, he says, a person’s skin could make the sunshine vitamin with 10 to 15 minutes of sunshine on the face and hands. The study in the journal Circulation was supported by the National Institutes of Health.